The present Applicant has disclosed in Japanese Patent Application No. 2003-293117 filed by the same Applicant that the above-mentioned compound A has an inhibitory action on integrase that is an en essential enzyme for the growth of HIV (Human Immunodeficiency Virus), which is a causative virus of AIDS (Acquired immunodeficiency Syndrome), and shows an anti-HIV effect (particularly Example 4-32 and Experimental Example).
In general, when a compound is used as a pharmaceutical product, chemical and physical stability of the compound is required so as to maintain quality and/or facilitate preservation. Not only the final pharmaceutical composition but also a compound as a synthetic starting material is desirably chemically and physically stable for the same reasons.
Therefore, such compound is preferably a crystal, particularly preferably a stable crystal. When the compound has crystal polymorphism, the most stable crystal is generally selected.
While the above-mentioned application describes compound A, no concrete description relating to the crystal form of compound A is found.